#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;

int main()
{

	int ori_price = 0;
	float discount = 0;
	scanf("%d %f", &ori_price, &discount);

	float fin_price = ori_price * discount;
	printf("%.2f", fin_price / 10.0);

	return 0;
}
